Throughout the nineteenth century, cosmopolitanism was an energizing force in Europe’s cultural and literary production. As the clash between cosmopolitanism and nationalism intensified in the nineteenth century, nationalist discourses glorified single ethnic or national entities while cosmopolitanism underlined the importance of interdependence in politics. Known for his originally cosmopolitan attitude to society, James Clarence Mangan (1803-1849) was an Irish translator and writer who used the properties of the East and the West in his translations, verse, and prose. Mangan’s authorial path was original, especially when the relationship between his work and givens of cosmopolitanism was considered. Although there are studies on his works, little attention has been paid to his prose work. In this study, Mangan’s stories titled “The Thirty Flasks,” “The Man in the Cloak. A very German Story,” and “The Three Rings” are analyzed concerning cosmopolitanism. Mangan’s characters experience transformation, which accounts for a unique blend of cosmopolitan subjectivities. Mangan’s characters also experience psychological and physical development, presenting an original treatment of cosmopolitanism which contributes to Mangan’s unique style, elsewhere noted as Manganesque. Mangan’s nationalism and cosmopolitanism submit a grey area, especially when his literary accomplishment as an Irish nationalist who intellectually fought against British imperialism is considered.